1. Field of the Invention
In one of its aspects, the present invention relates to a fluid treatment system for placement in a flanged pipe fluid conveyance system. In another of its aspects, the present invention relates to a method of installing a fluid treatment system in an existing piped fluid conveyance system.
2. Description of the Prior Art
Fluid treatment devices and systems are known. For example, U.S. Pat. Nos. 4,482,809, 4,872,980, 5,006,244 and Re.36,896 (all assigned to the assignee of the present invention) all describe gravity fed fluid treatment systems which employ ultraviolet (UV) radiation to inactivate microorganisms present in the fluid.
The devices and systems described in the '809, '980 and '244 patents generally include several UV lamps, each of which are mounted within sleeves extending between two support arms of the frames. The frames are immersed in the fluid to be treated which is then irradiated as required. The amount of radiation to which the fluid is exposed is determined by the proximity of the fluid to the lamps. One or more UV sensors may be employed to monitor the UV radiation output of the lamps and the fluid level is typically controlled, to some extent, downstream of the treatment device by means of level gates or the like. Since, at higher flow rates, accurate fluid level control is difficult to achieve in gravity fed systems, fluctuations in fluid level are inevitable. Such fluctuations could lead to non-uniform irradiation in the treated fluid.
However, disadvantages exist with the above-described systems. Depending on the quality of the fluid which is being treated, the sleeves surrounding the UV lamps periodically become fouled with foreign materials, inhibiting their ability to transmit UV radiation to the fluid. When fouled, at intervals which may be determined from historical operating data or by the measurements from the UV sensors, the sleeves must be manually cleaned to remove the fouling materials. Regardless of whether the UV lamp frames are employed in an open, channel-like system or a closed system, cleaning of the sleeves is impractical.
In open, channel-like systems, the modules comprising the sleeves are usually removed from the channel and immersed in a separate tank containing a suitable cleaning fluid. In closed systems, the device must be shut down and the sleeves are thereafter cleaned by charging with a suitable cleaning fluid or by removal of the lamps in the manner described for the open, channel-like systems. In either type of system, the operator must accept significant downtime of the system and/or invest significant additional capital to have in place sufficient redundant systems with appropriate control systems to divert the flow of fluid from the systems being cleaned.
The system described in the '896 patent is a significant advance in the art in that it obviates a number of disadvantages deriving from the devices and systems '809, '980 and '244 patents. Unfortunately, the system described in the '896 patent is ideally suited for use in an open, channel-like system and is not readily adaptable to be used in a completely closed system where the flow of fluid is fed under pressure in a pipe.
Closed fluid treatment devices are known—see, for example, U.S. Pat. No. 5,504,335 (assigned to the assignee of the present invention). The '335 patent teaches a closed fluid treatment device comprising a housing for receiving a flow of fluid. The housing comprises a fluid inlet, a fluid outlet, a fluid treatment zone disposed between the fluid inlet and the fluid outlet, and at least one radiation source module disposed in the fluid treatment zone. The fluid inlet, the fluid outlet and the fluid treatment zone are in a collinear relationship with respect to one another. The at least one radiation source module comprises a radiation source sealably connected to a leg which is sealably mounted to the housing. The radiation source is disposed substantially parallel to the flow of fluid. The radiation source module is removable through an aperture provided in the housing intermediate to fluid inlet and the fluid outlet thereby obviating the need to physically remove the device for service of the radiation source.
International Publication Number WO 01/25154 (assigned to the Assignee of the present invention) is another prior art reference which teaches a closed fluid treatment device. Specifically, this reference teaches a closed fluid treatment device comprising a housing for receiving a flow of fluid. The housing comprises a fluid inlet, a fluid outlet, a fluid treatment zone disposed between the fluid inlet and the fluid outlet, and at least one radiation source having a longitudinal axis disposed in the fluid treatment zone substantially transverse to the direction of fluid flow through the housing. The fluid inlet, the fluid outlet and the fluid treatment zone are arranged substantially collinearly with respect to one another. The fluid inlet comprises an opening characterized by two features. First, the opening has a cross-sectional area less than a cross-sectional area of the fluid treatment zone. Second, the opening has a largest diameter substantially parallel to the longitudinal axis of the radiation source disposed in the fluid treatment zone.
While the closed fluid treatment devices taught in U.S. Pat. No. 5,504,335 and in International Publication Number WO 01/25154 represent advances in the art, there is still room for improvement. Specifically, it is conventional in the art to custom build such closed fluid treatment devices, typically from stainless steel. In some cases, this can render the fluid treatment significantly more costly to acquire. It would be highly desirable to have a fluid treatment system capable of being utilized in a conventional pipe fitting. Such a device would result in significantly reducing direct manufacturing costs and, in some installations, allow for the system to be readily installed in existing piping systems.